Some ion-molecule reactions of hydrogen cyanide

1978 ◽  
Vol 31 (5) ◽  
pp. 963 ◽  
Author(s):  
CG Freeman ◽  
PW Harland ◽  
JP Liddy ◽  
MJ McEwan
Keyword(s):  
Gas Phase ◽  
Hydrogen Cyanide ◽  
Rate Coefficient ◽  
Rate Coefficients ◽  
Flowing Afterglow ◽  
Ion Molecule Reactions ◽  
Positive Ions

Rate coefficients for the reactions of several positive ions with HCN in the gas phase have been measured by the flowing afterglow technique. The reactions are all of the form ������������������������ X++HCN → products . where X+ and the corresponding rate coefficient, in units of cm3 molecule-1 s-1, are: X+ = HCN+ (k 9.8×10-10); C2N+ (k 3.1×10-10); CN+ (k 2.8×10-9 CH+ (k 3.2×10-9); H3O+ (k 4.5×10-9 and HCO+ (k 3.9×10-9).

Reactivity Trends in the Gas Phase Addition of Acetylene to N-protonated Aryl Radical Cations

2020 ◽  
Author(s):  
Oisin Shiels ◽  
P. D. Kelly ◽  
Cameron C. Bright ◽  
Berwyck L. J. Poad ◽  
Stephen Blanksby ◽  
...  
Keyword(s):  
Gas Phase ◽  
Ion Trap ◽  
Radical Cations ◽  
Rate Coefficients ◽  
Similar Process ◽  
Ion Molecule Reactions ◽  
Aromatic Radicals ◽  
Polycyclic Aromatic ◽  
Gas Phase Ion ◽  
Type Radical

<div> <div> <div> <p>A key step in gas-phase polycyclic aromatic hydrocarbon (PAH) formation involves the addition of acetylene (or other alkyne) to σ-type aromatic radicals, with successive additions yielding more complex PAHs. A similar process can happen for N- containing aromatics. In cold diffuse environments, such as the interstellar medium, rates of radical addition may be enhanced when the σ-type radical is charged. This paper investigates the gas-phase ion-molecule reactions of acetylene with nine aromatic distonic σ-type radical cations derived from pyridinium (Pyr), anilinium (Anl) and benzonitrilium (Bzn) ions. Three isomers are studied in each case (radical sites at the ortho, meta and para positions). Using a room temperature ion trap, second-order rate coefficients, product branching ratios and reaction efficiencies are reported. </p> </div> </div> </div>

scholarly journals Low temperature gas phase reaction rate coefficient measurements: Toward modeling of stellar winds and the interstellar medium

2019 ◽  
Vol 15 (S350) ◽  
pp. 382-383
Author(s):  
Niclas A. West ◽  
Edward Rutter ◽  
Mark A. Blitz ◽  
Leen Decin ◽  
Dwayne E. Heard
Keyword(s):  
Low Temperature ◽  
Interstellar Medium ◽  
Gas Phase ◽  
Low Temperatures ◽  
Reaction Rate ◽  
Rate Coefficient ◽  
Building Blocks ◽  
Rate Coefficients ◽  
Stellar Winds ◽  
Phase Reaction

AbstractStellar winds of Asymptotic Giant Branch (AGB) stars are responsible for the production of ∼85% of the gas molecules in the interstellar medium (ISM), and yet very few of the gas phase rate coefficients under the relevant conditions (10 – 3000 K) needed to model the rate of production and loss of these molecules in stellar winds have been experimentally measured. If measured at all, the value of the rate coefficient has often only been obtained at room temperature, with extrapolation to lower and higher temperatures using the Arrhenius equation. However, non-Arrhenius behavior has been observed often in the few measured rate coefficients at low temperatures. In previous reactions studied, theoretical simulations of the formation of long-lived pre-reaction complexes and quantum mechanical tunneling through the barrier to reaction have been utilized to fit these non-Arrhenius behaviours of rate coefficients.Reaction rate coefficients that were predicted to produce the largest change in the production/loss of Complex Organic Molecules (COMs) in stellar winds at low temperatures were selected from a sensitivity analysis. Here we present measurements of rate coefficients using a pulsed Laval nozzle apparatus with the Pump Laser Photolysis - Laser Induced Fluorescence (PLP-LIF) technique. Gas flow temperatures between 30 – 134 K have been produced by the University of Leeds apparatus through the controlled expansion of N2 or Ar gas through Laval nozzles of a range of Mach numbers between 2.49 and 4.25.Reactions of interest include those of OH, CN, and CH with volatile organic species, in particular formaldehyde, a molecule which has been detected in the ISM. Kinetics measurements of these reactions at low temperatures will be presented using the decay of the radical reagent. Since formaldehyde and the formal radical (HCO) are potential building blocks of COMs in the interstellar medium, low temperature reaction rate coefficients for their production and loss can help to predict the formation pathways of COMs observed in the interstellar medium.

Reactivity Trends in the Gas Phase Addition of Acetylene to N-protonated Aryl Radical Cations

2020 ◽  
Author(s):  
Oisin Shiels ◽  
P. D. Kelly ◽  
Cameron C. Bright ◽  
Berwyck L. J. Poad ◽  
Stephen Blanksby ◽  
...  
Keyword(s):  
Gas Phase ◽  
Ion Trap ◽  
Radical Cations ◽  
Rate Coefficients ◽  
Similar Process ◽  
Ion Molecule Reactions ◽  
Aromatic Radicals ◽  
Polycyclic Aromatic ◽  
Gas Phase Ion ◽  
Type Radical

<div> <div> <div> <p>A key step in gas-phase polycyclic aromatic hydrocarbon (PAH) formation involves the addition of acetylene (or other alkyne) to σ-type aromatic radicals, with successive additions yielding more complex PAHs. A similar process can happen for N- containing aromatics. In cold diffuse environments, such as the interstellar medium, rates of radical addition may be enhanced when the σ-type radical is charged. This paper investigates the gas-phase ion-molecule reactions of acetylene with nine aromatic distonic σ-type radical cations derived from pyridinium (Pyr), anilinium (Anl) and benzonitrilium (Bzn) ions. Three isomers are studied in each case (radical sites at the ortho, meta and para positions). Using a room temperature ion trap, second-order rate coefficients, product branching ratios and reaction efficiencies are reported. </p> </div> </div> </div>

Ion-molecule reactions in Trihalo- and Tetrahalo-methanes

1970 ◽  
Vol 23 (5) ◽  
pp. 893 ◽  
Author(s):  
NA McAskill
Keyword(s):  
Gas Phase ◽  
Cross Sections ◽  
High Pressures ◽  
Rate Coefficients ◽  
Ion Transfer ◽  
Ion Energy ◽  
Transfer Processes ◽  
Ion Molecule Reactions ◽  
Ionic Systems ◽  
Derivatives Of

The ion-molecule reactions of eight highly halogenated derivatives of methane were studied in the gas phase using a mass spectrometer operated at high pressures. The compounds studied were CHCl3, CHCl2F, CHClF2, CHF3, CCl4, CCl2F2, CClF3, and CF4. These ionic systems were found to be less reactive than those of methane or the methyl and methylene halides. The main reactions observed were described as being halide ion transfer processes. The energy dependence of the cross sections and the rate coefficients of the reactant ions were determined.� Many rate coefficients for reactions between ions and polar molecules were found to be independent of the ion energy. Brief studies of the negative spectra at high pressures were also made.

Hypovalent radicals. 4. Gas-phase studies of the ion-molecule reactions of cyclopentadienylidene anion radical in a flowing afterglow

1980 ◽  
Vol 102 (21) ◽  
pp. 6491-6498 ◽  
Author(s):  
Richard N. McDonald ◽  
A. Kasem Chowdhury ◽  
D. W. Setser
Keyword(s):  
Gas Phase ◽  
Anion Radical ◽  
Flowing Afterglow ◽  
Ion Molecule Reactions

Theoretical Prediction of CH3O and CH2OH Gas-Phase Decomposition Rate Coefficients

1986 ◽  
Vol 39 (12) ◽  
pp. 1929 ◽  
Author(s):  
PG Greenhill ◽  
BV Ogrady ◽  
RG Gilbert
Keyword(s):  
High Pressure ◽  
Theoretical Prediction ◽  
Gas Phase ◽  
Decomposition Rate ◽  
Rate Coefficient ◽  
Rate Coefficients ◽  
Phase Decomposition ◽  
Kinetic Schemes ◽  
Theoretical Predictions ◽  
Temperature Dependences

Theoretical predictions are made for the pressure and temperature dependences of two reactions involved in methanol combustion: (A) CH3O → CH2O + H and (B) CH2OH → CH2O + H. The calculations are carried out by using RRKM theory with a Gorin model for the activated complexes, with fall-off effects being taken into account by using the master equation. Results for the high-pressure rate coefficients (s-1) are (A) 3×1014 exp(-108 kJ mol-1 /RT), (B) 7×1014 exp(-124 kJ mol-1 /RT) at 1000 K. For the low-pressure limiting rate coefficient (cm3 s-1) over the range 600- 1000 K (A) 8×10-9 exp(-90 kJ mol-1 /RT); (B) 2×10-8 exp(-108 kJ mol-1 /RT). At 1000 K, the pressure at which the fall-off rate coefficients are one-half of their limiting high-pressure values are 3x108 Pa for both reactions. Formulae for inclusion of these reactions (including fall- off effects) over the range 300-2000 K and 10-2-106 Pa in modelling complex kinetic schemes are presented.

The kinetics of the pyrolysis of Cyclohexyl chloride.

1958 ◽  
Vol 11 (3) ◽  
pp. 314 ◽  
Author(s):  
ES Swinbourne
Keyword(s):  
Gas Phase ◽  
Hydrogen Chloride ◽  
Rate Coefficient ◽  
Initial Pressure ◽  
Order Reaction ◽  
Rate Coefficients ◽  
Homogeneous Reaction ◽  
First Order ◽  
Induction Periods ◽  
Kinetics Of

cycloHexy1 chloride has been shown to decompose in the gas phase at 318-385 �C almost exclusively to cyclohexene and hydrogen chloride. With clean glass-walled reactors the reaction was largely heterogeneous, but after the walls were coated with a carbonaceous film a homogeneous first-order reaction was found to predominate. For initial pressures within the range 4-40 cm mercury the rate coefficients for the homogeneous reaction were expressible as������� k = 5.88 x 1013exp(-50,000 cal/RT) sec-1. There was some evidence for the rate coefficient becoming pressure-dependent below 5-10 mm initial pressure of reactant. The reaction exhibited no induction periods and the velocity was virtually unaffected by the addition of large amounts of propene or cyclohexene and traces of chlorine or bromine. The results were consistent with a unimolecular elimination of hydrogen chloride.

scholarly journals Reactions of NO<sub>3</sub> with Aromatic Aldehydes: Gas Phase Kinetics and Insights into the Mechanism of the Reaction

2021 ◽  
Author(s):  
Yangang Ren ◽  
Li Zhou ◽  
Abdelwahid Mellouki ◽  
Véronique Daële ◽  
Mahmoud Idir ◽  
...  
Keyword(s):  
Gas Phase ◽  
Rate Coefficient ◽  
Theoretical Calculations ◽  
Aromatic Aldehydes ◽  
Reaction Pathways ◽  
Rate Coefficients ◽  
Gas Phase Kinetics ◽  
No3 Radical ◽  
Temperature And Pressure ◽  
Mechanism Of The Reaction

Abstract. Rate coefficients for the reaction of NO3 radicals with a series of aromatic aldehydes were measured in a 7300 liter simulation chamber at ambient temperature and pressure by relative and absolute methods. The rate coefficients for benzaldehyde (BA), ortho-tolualdehyde (O-TA), meta-tolualdehyde (M-TA), para-tolualdehyde (P-TA), 2,4-dimethyl benzaldehyde (2,4-DMBA), 2,5-dimethyl benzaldehyde (2,5-DMBA) and 3,5-dimethyl benzaldehyde (3,5-DMBA) were: k1 = 2.6 ± 0.3, k2 = 8.8 ± 0.8, k3 = 4.8 ± 0.5, k4 = 4.9 ± 0.5, k5 = 15.1 ± 1.4, k6 = 12.7 ± 1.2 and k7 = 6.2 ± 0.6, respectively, in the units of 10−15 cm3 molecule−1 s−1 at 298 ± 2 K. The rate coefficient k13 for the reaction of the NO3 radical with deuterated benzaldehyde (benzaldehyde-d1) was found to be half that of k1. The end product of the reaction with an excess of NOx was measured to be C6H5C(O)O2NO2. Theoretical calculations of aldehydic bond energies and reaction pathways indicate that NO3 radical reacts with aromatic aldehydes through the abstraction of aldehydic hydrogen atom. The atmospheric implications of the measured rate coefficients are briefly discussed.

Unimolecular Rearrangements and Fragmentations in the Gas Phase: [1,3] Sigmatropic Isomerizations and [2 + 2] Cycloreversions

2003 ◽  
Vol 56 (5) ◽  
pp. 453 ◽  
Author(s):  
Mohammad R. Ahmad ◽  
Steven R. Kass
Keyword(s):  
Gas Phase ◽  
Wide Temperature Range ◽  
Variable Temperature ◽  
Collision Induced Dissociation ◽  
Triple Quadrupole ◽  
Flowing Afterglow ◽  
Temperature Range ◽  
Sigmatropic Rearrangements ◽  
Ion Molecule Reactions ◽  
Trimethylsilyl Ethers

Trimethylsilyl ethers of 3-buten-2-ol, 1-vinylcyclopropanol, 1-vinylcyclobutanol, and cyclobutanol were treated with fluoride over a wide temperature range (–40 to 300°C) in a variable-temperature flowing afterglow–triple quadrupole device. The structures of the resulting alkoxides and enolates were probed by ion–molecule reactions and their collision-induced dissociation (CID) spectra. Activation energies were obtained for several anion-accelerated [1,3] sigmatropic rearrangements and [2 + 2] cycloreversions. The mechanisms for these isomerizations and fragmentations (stepwise versus concerted) and their synthetic potential are discussed.

Reaction of •OH with CHCl=CH-CHF2 and its atmospheric implication for future environmental-friendly refrigerant

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Olivier Holtomo ◽  
Lydia Rhyman ◽  
Mama Nsangou ◽  
Ponnadurai Ramasami ◽  
Ousmanou Motapon
Keyword(s):  
Gas Phase ◽  
Cross Sections ◽  
Radiative Forcing ◽  
Rate Coefficient ◽  
Computational Method ◽  
Rate Coefficients ◽  
Ir Absorption ◽  
Geometrical Structures ◽  
Atmospheric Lifetime ◽  
Environmental Friendly

Abstract In order to understand the atmospheric implication of the chlorinated hydrofluoroolefin (HFO), the geometrical structures and the IR absorption cross sections of the stereoisomers 1-chloro-3,3-difluoropropene were studied using the B3LYP/6-31G(3df) and M06-2X/6-31G(3df) methods in the gas phase. The cis-trans isomerization was assessed using the M06-2X/6-311++G(3df,p)//6-31+G(3df,p) method. The latter method was also employed for thermochemistry and the rate coefficients of the reactions of •OH with the cis- and trans-isomers in the temperature ranging from 200 to 400 K. The computational method CCSD/cc-pVTZ//M06-2X/6-31+G(3df,p) was used to benchmark the rate coefficients. It turns out that, the trans-isomer is more stable than cis-isomer and the trans- to cis-isomerization is thermodynamically unfavorable. The rate coefficient follows the Gaussian law with respect to the inverse of temperature. At the global temperature of stratosphere, the calculated rate coefficients served to estimate the atmospheric lifetime along with the photochemical ozone creation potential (POCP). This yielded lifetimes of 4.31 and 7.31 days and POCPs of 3.80 and 2.23 for the cis- and trans-isomer, respectively. The radiative forcing efficiencies gave 0.0082 and 0.0152 W m−2 ppb−1 for the cis- and trans-isomer, respectively. The global warming potential approached zero for both stereoisomers at 20, 100, and 500 years time horizons.

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